Control system for a tiltable vehicle

ABSTRACT

A vehicle of the present disclosure may include at least one pair of opposing wheels coupled to a tiltable central chassis by a four-bar linkage or the like, such that the wheels are configured to tilt in unison with the central chassis. A steering actuator and/or a tilting actuator may be discretely controllable by an electronic controller of the vehicle. The controller may include processing logic configured to maintain alignment between a median plane of the chassis and a net force vector caused by gravity and any induced centrifugal forces. Various control algorithms may be utilized to steer the vehicle along a desired path, either autonomously or semi-autonomously.

CROSS-REFERENCES

This application claims the benefit under 35 U.S.C. § 119(e) of thepriority of U.S. Provisional Patent Application Ser. No. 62/586,851(filed on Nov. 15, 2017), Ser. No. 62/587,984 (filed on Nov. 17, 2017),and Ser. No. 62/615,372 (filed on Jan. 9, 2018), the entireties of whichare hereby incorporated by reference for all purposes.

FIELD

This disclosure relates to systems and methods for automatically orsemi-automatically controlling a tiltable vehicle.

INTRODUCTION

Currently, most of the motor vehicles that are on the highways arefour-wheeled vehicles that tend to be larger, heavier and, as a resultless, fuel-efficient than three-wheeled motor vehicles. Despite the factthat four-wheeled vehicles may be seen to enjoy more widespread use andacceptance, there are several advantages that are provided by modernthree-wheeled vehicles. For example, under most circumstancesthree-wheel vehicles are, by their nature, more stable than four-wheeledvehicles due to the fact that three contact points will form a planeunder all circumstances, whereas four contact points will not. Anotheradvantage is that three-wheeled vehicles afford a nearly ideal wheelloading distribution for maximum tire traction in both acceleration andbraking situations.

Despite the advantages that three-wheeled vehicles enjoy overfour-wheeled vehicles, the main drawback of a three-wheeled vehicle isthat during a turn, rather than having two outside wheels in contactwith the road surface, the three-wheeled vehicle only has a singleoutside wheel that must bear the entire centrifugal load generated bythe vehicle while negotiating the turn. In this regard, the centrifugalforce tends to overload the outside tire causing the vehicle to slip outof the direction of the turn unless some additional means of forcecompensation is provided. Further, the three-wheeled vehicle geometryallows the force vector associated with the vehicle's center of gravityto quickly fall outside the wheelbase of the vehicle causing an unstablecondition and increasing the possibility of overturning the vehicle,and, in the case of a single rear-wheel drive, losing traction on therear wheel and entering a skid. To make this condition worse, as thecenter of gravity of the vehicle (including an operator and any loadbeing carried by the vehicle) raises higher, the potential for vehicleinstability and overturning becomes much greater.

The ability to overcome the aforementioned handling problems inthree-wheeled vehicles becomes even more important as more emphasis isplaced upon alternative fuel and/or hybrid vehicles with heavy batteryloads, and as the demand for self-driving or semi-autonomous vehiclesand mobile robotic systems rises.

Accordingly, there is a need for a control system for a tilting vehiclethat automatically maintains and enhances stability and handlingcharacteristics.

SUMMARY

The present disclosure provides systems, apparatuses, and methodsrelating to control systems for dynamically tiltable vehicles.

In some embodiments, a vehicle may include: a pair of wheels coupled toa tiltable central frame by a four-bar linkage configured such that thepair of wheels and the central frame are configured to tilt in unisonwith respect to a median plane of the central frame; a sensor configuredto detect directional information regarding a net force vector appliedto the central frame, wherein the net force vector is determined bygravity in combination with any applicable centrifugal force applied tothe central frame; a first actuator operatively coupled to the centralframe and configured to selectively tilt the central frame; a secondactuator operatively coupled to the pair of wheels and configured toselectively steer the pair of wheels; a controller including processinglogic configured to selectively control the first actuator and thesecond actuator in response to the directional information from thesensor to automatically maintain the net force vector in alignment withthe median plane of the central frame.

In some embodiments, a method for automatically operating a tiltablevehicle may include: sensing a net force vector on a central chassis ofa wheeled vehicle, the central chassis coupled to a pair of laterallydisposed wheels by a four-bar linkage assembly, wherein the centralchassis is tiltable from side to side and the four-bar linkage assemblyis configured to tilt the wheels in unison with the central chassis, andwherein the central chassis defines a median plane; in response toreceiving information relating to a desired travel path, comparing aspeed of the vehicle to a first threshold and a second threshold greaterthan the first threshold; and in response to the speed of the vehiclebeing less than the first threshold, turning the vehicle bysimultaneously and automatically steering the wheels and causing atilting of the central chassis, such that a misalignment between the netforce vector and the median plane is minimized.

Features, functions, and advantages may be achieved independently invarious embodiments of the present disclosure, or may be combined in yetother embodiments, further details of which may be seen with referenceto the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a rider on an illustrative tiltable vehicle,in accordance with aspects of the present teachings.

FIG. 2 is a front elevation view of the vehicle of FIG. 1, tilted withrespect to a median plane of the vehicle.

FIG. 3 is a schematic view of another illustrative tiltable vehicle, inaccordance with aspects of the present teachings.

FIG. 4 is a schematic front view of an illustrative vehicle wheelassembly suitable for use in a vehicle of the present teachings.

FIG. 5 is a schematic block diagram of the vehicle of FIG. 3 andselected components of a control system thereof.

FIG. 6 is a schematic front view of a wheel assembly portion of atiltable vehicle, in accordance with aspects of the present teachings.

FIG. 7 is another schematic front view of the vehicle of FIG. 6,depicting the wheel assembly in a tilted position.

FIG. 8 is a front view of an illustrative vehicle having a wheelassembly and a selected tilt actuator, in accordance with aspects of thepresent teachings.

FIG. 9 is another front view of the vehicle of FIG. 8, depicting thevehicle in a tilted position.

FIG. 10 is a front view of another illustrative vehicle having a wheelassembly and another selected tilt actuator, in accordance with aspectsof the present teachings.

FIG. 11 is another front view of the vehicle of FIG. 10, depicting thevehicle in a tilted position.

FIG. 12 is a schematic front view of yet another illustrative wheelassembly having another selected tilt actuator, in accordance withaspects of the present teachings.

FIG. 13 is another schematic front view of the wheel assembly of FIG.12, depicting the wheel assembly in a tilted position.

FIG. 14 is a front view of yet another illustrative vehicle having awheel assembly and a selected tilt actuator, in accordance with aspectsof the present teachings.

FIG. 15 is another front view of the vehicle of FIG. 14, depicting thevehicle in a tilted position.

FIG. 16 is a schematic front view of yet another illustrative wheelassembly having a selected tilt actuator, in accordance with aspects ofthe present teachings.

FIG. 17 is another schematic front view of the wheel assembly of FIG.16, depicting the wheel assembly in a tilted position.

FIG. 18 is a front view of an illustrative linkage component suitablefor use in a vehicle wheel assembly, in a first position.

FIG. 19 is another front view of the linkage component of FIG. 18,depicting the linkage component in a second position.

FIG. 20 is a front view of another illustrative linkage componentsuitable for use in a vehicle wheel assembly, in a first position.

FIG. 21 is another front view of the linkage component of FIG. 20,depicting the linkage component in a second position.

FIG. 22 is a front view of an illustrative tiltable vehicle havingillustrative wheel assembly linkage components, in accordance withaspects of the present teachings.

FIG. 23 is another front view of the vehicle of FIG. 22, depicting thevehicle in a tilted position.

FIG. 24A is a partial, isometric, schematic view of another illustrativetiltable vehicle having an A-frame linkage, with a frame tilted in afirst direction in accordance with aspects of the present teachings.

FIG. 24B is a partial, isometric, schematic view of the vehicle of FIG.24A, tilted in a second direction.

FIG. 25 is an isometric view of an illustrative vehicle steeringassembly suitable for use in vehicles of the present teachings.

FIG. 26 is a side view of yet another illustrative tiltable vehicle, inaccordance with aspects of the present teachings.

FIG. 27 is a front view of yet another illustrative tiltable vehicle, ina neutral position.

FIG. 28 is another front view of the vehicle of FIG. 27, depicting thevehicle in a turning position.

FIG. 29 is yet another front view of the vehicle of FIG. 27, depictingthe vehicle in a turning and tilted position.

FIG. 30 is yet another front view of the vehicle of FIG. 27, depictingthe vehicle in a tilted position.

FIG. 31 is a schematic front view of yet another illustrative tiltablevehicle, in accordance with aspects of the present teachings.

FIG. 32 is another schematic front view of the vehicle of FIG. 31,depicting the vehicle remaining upright while traversing an obstacle.

FIG. 33 is yet another schematic front view of the vehicle of FIG. 31,depicting the vehicle in a tilted position.

FIG. 34 is yet another schematic front view of the vehicle of FIG. 31,depicting the vehicle in a tilted position while traversing an obstacle.

FIG. 35 is a flow chart depicting steps of an illustrative method forcontrolling a tiltable vehicle according to the present teachings.

FIG. 36 is another flow chart depicting steps of an illustrative methodfor controlling a tiltable vehicle according to the present teachings.

DETAILED DESCRIPTION

Various aspects and examples of a vehicle having automated tilt and/orsteering controls, as well as related methods, are described below andillustrated in the associated drawings. Unless otherwise specified, avehicle in accordance with the present teachings, and/or its variouscomponents, may contain at least one of the structures, components,functionalities, and/or variations described, illustrated, and/orincorporated herein. Furthermore, unless specifically excluded, theprocess steps, structures, components, functionalities, and/orvariations described, illustrated, and/or incorporated herein inconnection with the present teachings may be included in other similardevices and methods, including being interchangeable between disclosedembodiments. The following description of various examples is merelyillustrative in nature and is in no way intended to limit thedisclosure, its application, or uses. Additionally, the advantagesprovided by the examples and embodiments described below areillustrative in nature and not all examples and embodiments provide thesame advantages or the same degree of advantages.

This Detailed Description includes the following sections, which followimmediately below: (1) Definitions; (2) Overview; (3) Examples,Components, and Alternatives; (4) Advantages, Features, and Benefits;and (5) Conclusion. The Examples, Components, and Alternatives sectionis further divided into subsections A and B, each of which is labeledaccordingly.

Definitions

The following definitions apply herein, unless otherwise indicated.

“Substantially” means to be more-or-less conforming to the particulardimension, range, shape, concept, or other aspect modified by the term,such that a feature or component need not conform exactly. For example,a “substantially cylindrical” object means that the object resembles acylinder, but may have one or more deviations from a true cylinder.

“Comprising,” “including,” and “having” (and conjugations thereof) areused interchangeably to mean including but not necessarily limited to,and are open-ended terms not intended to exclude additional, unrecitedelements or method steps.

Terms such as “first”, “second”, and “third” are used to distinguish oridentify various members of a group, category, or the like, and are notintended to show serial or numerical limitation.

“AKA” means “also known as,” and may be used to indicate an alternativeor corresponding term for a given element or elements.

The terms “inboard,” “outboard,” “forward,” “rearward,” and the like areintended to be understood in the context of a vehicle or host vehicle(if describing a component). For example, “outboard” may indicate arelative position that is laterally farther from the centerline of thevehicle, or a direction that is away from the vehicle centerline.Conversely, “inboard” may indicate a direction toward the centerline, ora relative position that is closer to the centerline. Similarly,“forward” means toward the front portion of the vehicle, and “aft” meanstoward the rear of the vehicle. In the absence of a host vehicle, thesame directional terms may be used as if the vehicle were present. Forexample, even when viewed in isolation, a device may have a “forward”edge, based on the fact that the device would be installed with the edgein question facing in the direction of the front portion of the hostvehicle.

Directional terms such as “up,” “down,” “vertical,” “horizontal,” andthe like should be understood in the context of the particular vehiclebeing described, in its normal operating configuration. For example, avehicle may be oriented around defined X, Y, and Z axes. In thoseexamples, the X-Y plane will define horizontal, with up being defined asthe positive Z direction and down being defined as the negative Zdirection. In general, as used herein, the Z axis will be aligned withthe force due to gravity.

“Coupled” means connected, either permanently or releasably, whetherdirectly or indirectly through intervening components, and (depending onthe context) is not necessarily limited to physical connection(s).

“Resilient” describes a material or structure configured to be deformedelastically under normal operating loads (e.g., when compressed) and toreturn to an original shape or position when unloaded.

“Rigid” describes a material or structure configured to be stiff,non-deformable, or substantially lacking in flexibility under normaloperating conditions.

“Processing logic” may include any suitable device or hardwareconfigured to process data by performing one or more logical and/orarithmetic operations (e.g., executing coded instructions). For example,processing logic may include one or more processors (e.g., centralprocessing units (CPUs) and/or graphics processing units (GPUs)),microprocessors, clusters of processing cores, FPGAs (field-programmablegate arrays), artificial intelligence (AI) accelerators, digital signalprocessors (DSPs), and/or any other suitable combination of logichardware.

Overview

In general, a vehicle of the present teachings may include at least onepair of tiltable wheels and a control system having processing logicconfigured to automatically tilt the chassis of the vehicle and in somecases actively steer the wheels of the vehicle to guide the vehicle downa selected path while maintaining a median plane of the vehicle chassisin alignment with a net force vector resulting from gravity andcentrifugal force (if any). The vehicle may be of any suitable designconfigured to result in a coordinated and substantially identicaltilting of the chassis and the wheels. For example, a steering orsuspension system of the vehicle may comprise a four-bar parallelogramlinkage, coupling the left and right wheels to a central chassis.Examples of this type of vehicle are described below. In some cases, thevehicle may comprise a robotic vehicle, a semi-autonomous vehicle, or afly-by-wire vehicle.

Methods and systems of the present disclosure may, for example, providefor the delivery of articles, objects, products, or goods from onelocation to another location using the wheeled vehicle. Control methodsmay be computer implemented, either partially or totally. As describedabove, the wheeled vehicle may optionally be remotely controlled,semiautonomous, or mixed autonomous. The vehicle may optionally be oneor a plurality of wheeled vehicles, for example one of a plurality ofidentical wheeled vehicles. In some embodiments, the wheeled vehicle mayoptionally be a driverless wheeled vehicle, which may be referred to asdriverless vehicle or robot, an autonomous vehicle or robot, anautonomous wheeled vehicle or robot or any combination of such terms.The system of the present disclosure may be referred to as a wheeledvehicle or robotic delivery system, a driverless vehicle or roboticdelivery system, an autonomous vehicle or robotic delivery system, adriverless or autonomous delivery system or any combination of theforegoing. The method and system of the present disclosure mayoptionally be used on an indoor or an outdoor land transportationnetwork, which may include roads, bike paths, sidewalks, alleys, paths,crosswalks, any route on which a wheeled vehicle may travel or anycombination of the foregoing. The transportation network of the presentdisclosure may be referred to as an outdoor network, an outdoortransportation network, a land transportation network, or the like.

Electromechanically controllable variables of the vehicle may includechassis tilt with respect to the wheel linkage, steering of the wheels,throttle or vehicle speed, and braking. In general, the control systemis configured to keep centrifugal and gravitational forces inequilibrium when turning, so that the combined centrifugal andgravitational vectors create a net force vector parallel to the chassisand wheel median planes. By directing the combined forces parallel tothe chassis, stress on the vehicle suspension components (as well asriders where applicable) is reduced, rollover risk is decreased, andtraction in a turn is improved or maximized.

The ideal leaning position of the chassis may be achieved through acombination of actuators and control software to create the desiredperformance. In some examples, tilt and steering angles are discretelycontrolled for a given turn. In general, the tilt to steer ratio iscontrolled, depending on speed and terrain, and higher speed leads tomore vehicle chassis lean, less wheel steering. The tilt experienced atthe chassis is a sum of the angle of the road surface plus the angle ofthe wheel linkage articulation. Detecting the level of the surface (orthe chassis tilt displacement to correct) could in some cases be doneusing a suitable sensor near the road surface. However, it may be moreeffective to determine and maintain the absolute tilt angle of thechassis by measuring its relationship to the net force vector caused bygravity and any centrifugal forces.

In some cases, the interaction of crowned tires with the terrain must beaccounted for, as the crowned shape of some wheels may produce scrubwhen tracking along the side of the wheel in a given turn vector overuneven or slanted terrain. For tilting three wheeled vehicles,understeering or oversteering may be needed, depending on terrain, tocounter the natural effect of the crowned wheel to oversteer orundersteer into the turn. Generally speaking, this tire scrub ispreferable to loss of the desired path of the vehicle.

Aspects of control systems described herein may be embodied asprocessing logic including a computer method, computer system, orcomputer program product. Accordingly, aspects of the control systemsmay take the form of an entirely hardware embodiment, an entirelysoftware embodiment (including firmware, resident software, micro-code,and the like), or an embodiment combining software and hardware aspects,all of which may generally be referred to herein as a “circuit,”“module,” or “system.” Furthermore, aspects of the control systems maytake the form of a computer program product embodied in acomputer-readable medium (or media) having computer-readable programcode/instructions embodied thereon.

Any combination of computer-readable media may be utilized.Computer-readable media may be a computer-readable signal medium and/ora computer-readable storage medium. A computer-readable storage mediummay include an electronic, magnetic, optical, electromagnetic, infrared,and/or semiconductor system, apparatus, or device, or any suitablecombination of these. More specific examples of a computer-readablestorage medium may include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, asolid state memory, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, and/orany suitable combination of these and/or the like. In the context ofthis disclosure, a computer-readable storage medium may include anysuitable non-transitory, tangible medium that may contain or store aprogram for use by or in connection with an instruction executionsystem, apparatus, or device.

A computer-readable signal medium may include a propagated data signalwith computer-readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, and/or any suitable combination thereof. Acomputer-readable signal medium may include any computer-readable mediumthat is not a computer-readable storage medium and that is capable ofcommunicating, propagating, or transporting a program for use by or inconnection with an instruction execution system, apparatus, or device.

Program code embodied on a computer-readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, and/or the like, and/or any suitablecombination of these.

Computer program code for carrying out operations for aspects of thecontrol systems may be written in one or any combination of programminglanguages, including an object-oriented programming language such asJava, C++, and/or the like, and conventional procedural programminglanguages, such as C. Mobile apps may be developed using any suitablelanguage, including those previously mentioned, as well as Objective-C,Swift, C #, HTML5, and the like. The program code may execute entirelyon a user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer, or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), and/or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider).

Aspects of control systems are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatuses,systems, and/or computer program products. Each block and/or combinationof blocks in a flowchart and/or block diagram may be implemented bycomputer program instructions. The computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block(s). In some examples, machine-readableinstructions may be programmed onto a programmable logic device, such asa field programmable gate array (FPGA).

These computer program instructions may also be stored in acomputer-readable medium that may direct a computer, other programmabledata processing apparatus, and/or other device to function in aparticular manner, such that the instructions stored in thecomputer-readable medium produce an article of manufacture includinginstructions which implement the function/act specified in the flowchartand/or block diagram block(s).

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, and/or other device tocause a series of operational steps to be performed on the device toproduce a computer-implemented process such that the instructions whichexecute on the computer or other programmable apparatus provideprocesses for implementing the functions/acts specified in the flowchartand/or block diagram block(s).

Any flowchart and/or block diagram in the drawings is intended toillustrate the architecture, functionality, and/or operation of possibleimplementations of systems, methods, and computer program productsaccording to aspects of the control systems. In this regard, each blockmay represent a module, segment, or portion of code, which comprises oneor more executable instructions for implementing the specified logicalfunction(s). In some implementations, the functions noted in the blockmay occur out of the order noted in the drawings. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. Each block and/orcombination of blocks may be implemented by special purposehardware-based systems (or combinations of special purpose hardware andcomputer instructions) that perform the specified functions or acts.

Examples, Components, and Alternatives

The following sections describe selected aspects of exemplary vehiclesand control systems, as well as related systems and/or methods. Theexamples in these sections are intended for illustration and should notbe interpreted as limiting the scope of the present disclosure. Eachsection may include one or more distinct embodiments or examples, and/orcontextual or related information, function, and/or structure.

A. Illustrative Vehicles and Controls

As shown in FIGS. 1-26, this section describes illustrative tiltablevehicles and associated electromechanical controls. These vehicles areexamples of the tiltable vehicle and related controls described in theOverview above.

With reference to FIGS. 1-2, a three-wheeled tilting vehicle 12 is shownand generally illustrated with a wheel linkage assembly 10 installed ata front end (also referred to as a suspension assembly). Vehicle 12 isdepicted in an upright (see FIG. 1) and a tilted (see FIG. 2) positionand is depicted in the context of a wheeled vehicle. Vehicle 12 includesa central frame 14 (AKA chassis) having a front, a rear, and a supportportion 16 for a rider 18. Front wheel linkage assembly 10 may beattached to the front of the central frame 14 at pivots 19. Front wheellinkage assembly 10 includes a top suspension bar 20 and a bottomsuspension bar 22, each of which has a respective left end and rightend. Wheel linkage assembly 10 further includes a left suspension bar 24and a right suspension bar 26 each having respective top and bottomends.

The geometry of wheel linkage assembly 10 is arranged such that the leftends of top and bottom suspension bars 20, 22 are pivotally attached tothe respective top and bottom ends of left suspension bar 24 and theright ends of top and bottom suspension bars 20, 22 are pivotallyattached to the respective top and bottom ends of right suspension bar26 at pivots 17. Accordingly, top and bottom suspension bars 20, 22 aresubstantially parallel to one another and left and right suspension bars24, 26 are substantially parallel to one another. A central portion ofthe top and bottom suspension bars are pivotally affixed to the front ofcentral frame 14. As described above, the geometry of wheel linkageassembly 10 is implemented as a four-bar linkage. Specifically, the foursuspension bars 20, 22, 24, 26 of assembly 10 are arranged in aparallelogram shape wherein top and bottom suspension bars 20, 22 aresubstantially parallel along the top and bottom of the suspensionassembly and left and right suspension bars 24, 26 are substantiallyparallel to one another along the left and right sides of the suspensionassembly. The ends of each of the suspension bars 20, 22, 24, 26 arepivotally attached to one another to form a hinged parallelogram.

In some examples, such as the one depicted in FIGS. 1 and 2, bottomsuspension bar 22 may be enlarged in depth and extended rearwardly toform a storage compartment 28 that provides storage capacity forinstallation of heavy items such as battery banks 30 to preserve alowered center of gravity for vehicle 12. In this manner, storagecompartment 28 provides a location for the placement of batteries 30that power vehicle 12 in a relatively low position to enhance thestability and lower the center of gravity. In particular, because bottomsuspension bar 22 (in this example) does not tilt relative to centralframe 14, the weight of batteries 30 is removed from the tilting aspectsof the suspension assembly. As a result, the tilting mass of vehicle 12remains light and nimble. This allows vehicle 12 to have lightweighthandling response and overall feel while still carrying a substantialbattery load.

Vehicle 12 is a pivoting vehicle having a first vertical axis 32 ofcentral frame 14 defining a median plane dividing the frame or chassisinto left and right portions, as well as second and third vertical axes34, 36 running through each of two spaced tires 38, 40 (AKA wheels).These three axes are configured to remain parallel as vehicle 12 tilts.Legs 42 of user 18 may be used in some examples to control the tilt ofvehicle 12, although automated examples (in some cases unmanned) aredescribed below. Whether the vehicle has two, three, four, or morewheels, central frame 14 is coupled to at least two wheels 38, 40 thattilt as central frame 14 tilts (i.e., in unison), so that these elementsremain in their parallel orientation with respect to the axes justdefined.

The arrangement of the present example facilitates the free-leaningperformance of a motorcycle without the need for a high level oftraction between the tires and the travel surface for the vehicle toremain upright. As a result, the vehicle may be operated on snow, ice,dirt, etc., more safely. Generally, travel surface interfaces (e.g.,tires, skis, treads, etc.) for traveling over a surface 44 are affixedto left and right suspension bars 24, 26 and to the rear of centralframe 14 to allow vehicle 12 to be operated on surface 44. In theexample depicted, a three-wheeled vehicle 12 has travel surfaceinterfaces in the form of a single rear drive wheel 46 and two forwardwheels 38, 40. However, it should be appreciated by one skilled in theart that the teachings of the present disclosure apply to a two- orfour-wheeled vehicle, as well as to water craft operating on pontoons orsnow vehicles operating on skis.

To facilitate steering of vehicle 12, wheel linkage assembly 10 includesfront wheels 38, 40 mounted to respective spindles 48 that are pivotallycoupled to left and right suspension bars 24, 26 and connected tire rods29. As vehicle 12 is tilted, spindles 48 and wheels 38, 40 mounted tothe left and right suspension bars 24, 26 at pins 17 also tilt tomaintain the geometry of the parallelogram. In this respect, as vehicle12 is tilted, left and right wheels 38, 40 are also tilted and remain ina substantially parallel relation to central frame 14. In addition,however, the ability to pivot wheel spindles 48 relative to wheellinkage assembly 10 on bearings 25 allows wheels 38, 40 to be turned tofacilitate cornering of vehicle 12.

In some examples, the four-bar linkage of wheel linkage assembly 10 iscoupled onto the front end of a motorized version of vehicle 12, such asa moped, electric bike, or motorcycle. In this manner, rear wheel 46serves as the drive wheel and the front wheel is replaced with wheellinkage assembly 10 and front wheels 38, 40. In this configuration,spindles 48 for front wheels 38, 40 are mounted to left and rightsuspension bars 24, 26 in a manner that allows spindles 48 and wheels38, 40 to pivot around the axis of left and right suspension bars 24,26. Moreover, spindles 48 are interconnected by an assembly including atie rod that is also connected to a steering, linkage thereby allowingthe user (or an automated controller) to steer vehicle 12. To furtherassist in stabilizing vehicle 12, front wheels 38, 40 may have at leasta small amount of caster to the rear of the wheel linkage assembly 10 tofacilitate self-centering of the steering and a slight amount of camberto urge vehicle 12 to a normal upright position.

An illustrative wheeled vehicle 300 similar to vehicle 12 is depictedschematically in FIG. 3. Wheeled vehicle 300 includes a chassis 322 (AKAa frame) having a first end 323 and an opposite second end 324. One ormore wheels are rotatably coupled to first end 323 of chassis 322, andone or more wheels are rotatably coupled to second end 324 of chassis322. In some embodiments, first and second wheels 326, 327 are rotatablycoupled to first end 323 and a single wheel 328 is rotatably coupled tosecond end 324. First end 323 may be the front or rear of vehicle 300,and in some embodiments the first end is the front end of the vehicle.In some embodiments, first and second wheels 326, 327 are the front leftwheel and front right wheel, respectively, of wheeled vehicle 300.

A suspension assembly 331 (AKA wheel assembly, wheel linkage, linkageassembly) is provided for coupling first and second wheels 326, 327 tochassis 322. Suspension assembly 331 may include any suitable linkage.In some examples, suspension assembly 331 includes a crossmember 332having a first or left end 332A and a second or right end 332B. A firstbracket 333 is connected to first end 332A of crossmember 332 and asecond bracket 334 is connected to second end 332B of crossmember 332.Crossmember 332 and brackets 333, 334 may be made from any suitablematerial, such as a metal, and brackets 333, 334 may be welded orotherwise rigidly secured to crossmember 332.

First and second wheels 326, 327 are pivotably coupled to respectiveends of suspension assembly 331. In some embodiments, a pivot assembly336 is provided at each end of suspension assembly 331 for couplingwheels 326, 327 to the suspension assembly. Pivot assemblies 336facilitate rotation of wheels 326, 327 in a manner that facilitatesturning and/or steering of the wheels relative to suspension assembly331 (e.g., about respective vertical or Z pivot axes). In someembodiments, each pivot assembly 336 includes a spindle axle 337pivotably coupled to the respective bracket 333, 334, e.g., by a pivotpin or bolt extending through the spindle axle and connected at each endto the respective bracket. A nut and/or any other suitable fastener maybe provided for coupling to one end of the pivot pin for securing thepivot pin to the respective bracket 333, 334.

First and second wheels 326, 327 are rotatably coupled to respectiveends of suspension assembly 331. In some embodiments, a suitable wheelrotation assembly 346 is provided at each end of suspension assembly 331for coupling wheels 326, 327 to the suspension assembly in any mannerthat permits rotation of the wheels relative to the suspension assembly,for example about a horizontal (Y) axis, perpendicular to the vertical(Z) pivot axis of the wheel. Each wheel rotation assembly 346 mayinclude an axle, a bearing, and/or any other suitable mechanism forpermitting rotation of the wheel on a vehicle.

Wheeled vehicle 300 may include any suitable steering mechanism orassembly 356 for causing each of first and second wheels 326, 327 topivot about their respective ends of suspension assembly 331 to permitsteering of vehicle 300. Suitable steering mechanisms 356 include knownassemblies or mechanisms for steering automobiles, trucks, and/or anyother vehicles suitable for traveling on transportation networks of anytype. In some embodiments, steering assembly 356 includes first andsecond steering rods 357, 358 (AKA tie rods or pivot rods or arms),which are coupled to a steering shaft 359 such that rotation of steeringshaft 359 causes steering rods 357, 358 to move laterally relative tothe steering shaft and cause wheels 326, 327 to pivot substantially inunison about their respective pivot axes. In some embodiments, each ofsteering rods 357, 358 has an outer end pivotably coupled to therespective spindle axle 337, e.g., to an arm 361 of the axle, and aninner end coupled to the lower or bottom end of steering shaft 359.Longitudinal movement of one of the steering rods 357, 358 causes therespective arm 361 to rotate the respective spindle axle 337 about itspivot axis. In some embodiments, the bottom end of the steering shaftincludes a coupling bracket 362 extending perpendicularly with respectto shaft 359 and having first and second spaced-apart attachmentmechanisms pivotably coupled to the inner end of the first and secondsteering rods 357, 358. Steering mechanism 356 may include any othersuitable known mechanisms, such as rack and pinion assemblies, etc., forcausing the first and second steering rods 357, 358 to movelongitudinally in opposite first and second directions upon rotation ofsteering shaft 359. A steering handlebar or wheel 366, or any othersuitable human hand-grippable element, may be secured to steering shaft359 for permitting a human driver to operate steering mechanism 356.

Chassis 322 includes a neck or stem 371 (AKA steering tube) at front end323 of the chassis. Steering shaft 359 is rotatably carried by stem 371,e.g., by a rotational joint or assembly that may include one or morebearings. A top tube 372 extends rearwardly from the top end of stem371, and a bottom tube or downtube 373 extends rearwardly from thebottom end of stem 371. A center post or seat tube 374 is joined to therespective rear ends of each of top tube 372 and bottom tube 373. Rearwheel 328 is rotatably coupled to second or rear end 324 of chassis 322.For example, a bottom arm or fork 376, which may be referred to as asoft tail, may be pivotably coupled to the rear of seat tube 324, e.g.,at the bottom end of the seat tube, by a pivot assembly 377 configuredto pivot about a horizontal (Y) axis. A wheel rotation assembly 347 isdisposed at the end of fork 376 for coupling wheel 328 to rear end 324of chassis 322. A spring and/or any other suitable deflecting suspensionmember 381 may be included in vehicle 300 for dampening and/orrestricting pivoting of fork 376 about pivot assembly 377. In someembodiments, spring 381 has a first end coupled to the center portion ofchassis 322 (e.g., to the top end of seat tube 374) and an oppositesecond end coupled to the free end of fork 376 (e.g., adjacent rearwheel rotation assembly 347). A seat 382 for permitting a human operatorto sit on vehicle 300 may also be provided.

Chassis 322 is tiltable side to side about an axis (e.g., a horizontal(X) axis), so as to be tiltable relative to the surface on which thevehicle is traveling (i.e., to the left and right). In some examples,chassis 322 may be secured to suspension assembly 331 in a manner thatpermits chassis 322 to pivot or tilt relative to the suspensionassembly, and thus relative to front wheels 326, 327. In some examples,chassis 322 is pivotably coupled by a pivot assembly 386 joined to thecenter of suspension assembly 331 (e.g., at crossmember 332) and thebottom of stem 371 of the chassis. Pivot assembly 386 may be referred toas a rotational joint or tilt rotational joint. Pivot assembly 386permits stem 371 to pivot about a horizontal (X) axis. Such pivotingand/or tilting of chassis 322 may compensate for lateral accelerationsand/or centrifugal forces exerted on chassis 322 and any driver duringoperation of vehicle 300 (see below). Such lateral accelerations and/orcentrifugal forces may occur, for example, during turning of vehicle300.

Wheeled vehicle 300 may include one or more containers for storingand/or transporting goods. As an example, a first container 391 is shownin dashed lines in FIG. 3, coupled to the front of chassis 322, and asecond container 392 is shown in dashed lines coupled to the rear ofchassis 322.

Vehicle 300 may optionally include at least one mechanism, assembly,apparatus, and/or device of any suitable type, which may optionally becarried by one of the containers, for removing or assisting in theremoval of the contents of the container, for moving articles betweencontainers, for placing or moving or assisting in the placement ormovement of articles into the container, or any combination theforegoing. The at least one mechanism may include a crane, a pickup orother arm, a scoop, a shovel, a pulley, a claw, a magnet, a conveyor, abelt, rollers, balls, a movable surface, a movable wall, a slide, agrasping device, and/or any combination the foregoing. The at least onetransport mechanism may optionally be inside one of the containers.

Wheel 326, wheel 327, and/or wheel 328 may be driven by one or moremotors or drive actuators 396, which may optionally be controlled by acontroller for moving wheeled vehicle 300. In some embodiments, aplurality of wheels are driven by one or more motors, or are motorized.In some embodiments, front wheel 326 and front wheel 327 are driven byone or more motors, for example by one respective motor for each wheel.In some embodiments, all of the wheels of wheeled vehicle 300 are drivenby one or more respective motors, or motorized. The foregoing motors ordrive actuators may each be of any suitable type, for example anelectric motor or actuator. In some embodiments, each of the wheels isinternally powered by an electric motor or actuator, e.g., a hub motor,a scooter hub motor, a wheel motor, a wheel hub drive, and/or anotherin-wheel motor of any suitable type. Vehicle 300 may be powered by asingle actuator or motor, e.g., an electric motor carried by chassis 322and coupled to one or more of the wheels, for example by a chain drive,a belt drive, a shaft drive, and/or any combination of the foregoing.

Steering mechanism 356 of vehicle 300 may be driven by one or moremotors or steering actuators 101, which may optionally be controlled bythe controller for steering the vehicle. In some embodiments, one ormore steering actuators 101 may be carried by chassis 322 for causingrotation of steering shaft 359 relative to the chassis. For example, asteering actuator 101 may be provided at the top of stem 371 forpivoting and/or rotating steering shaft 359 within stem 371. In someembodiments, one or more steering actuators 101 may be provided onsuspension assembly 331 for causing wheels 326, 327 to pivot aboutrespective pivot assemblies 336 in any suitable manner. For example, oneor more steering actuators 101 may be provided to move one or both ofsteering rods 357, 358, one or both of spindle axles 337, and/or anycombination the foregoing. The foregoing motors or actuators may each beof any suitable type, for example an electric motor or actuator.

Pivot assembly 386 of wheeled vehicle 300 may be driven by one or moremotors or actuators 102, which may optionally be controlled by anelectronic controller, or motorized or actuated, for tilting chassis 322relative to the surface on which the wheeled vehicle is traveling, orany line extending substantially parallel to such surface. Each of suchone or more motors or actuators may be referred to as a tilting actuator102. In some embodiments, one or more tilting actuators 102 may becarried by chassis 322 for causing the chassis to tilt relative tosuspension assembly 331, and thus cause the chassis 322 to tilt relativeto the surface on which vehicle 300 is traveling. For example, a tiltingactuator 102 may be provided in the vicinity of pivot assembly 386,e.g., as shown in FIG. 3, carried by bottom tube 373 of chassis 322. Oneor more tilting actuators 102 may be provided within pivot assembly 386,mounted on suspension assembly 331, mounted on stem 371, mounted onbottom tube 373, and/or any combination the foregoing. The foregoingmotors or actuators may be of any suitable type, for example an electricmotor or actuator.

Any or all of wheels 326, 327, 328 of wheeled vehicle 300 may be slowedand/or stopped by a braking mechanism of any suitable type (not shown),for example any suitable known braking mechanism utilized onautomobiles, trucks, motorcycles and/or other vehicles suitable fortraveling on transportation networks of any type. In some embodiments,each of the wheels 326, 327, 328 has a separate braking mechanism forslowing or stopping the respective wheel. Each of the braking mechanismsof wheeled vehicle 300 may be optionally controlled by a motor oractuator 106, which may optionally be controlled by the controller forslowing, braking, and/or stopping the respective wheel of vehicle 300.Each of such motors or actuators may be referred to as a brakingactuator 106. In some embodiments, a separate braking actuator 106 iscarried by chassis 322 in the vicinity of one or all of wheel rotationassemblies 346 of vehicle 300. In some embodiments, a braking actuator106 is carried by chassis 322 in the vicinity of each wheel rotationassembly 346 for slowing and/or stopping the respective wheel 326, 327,328 of vehicle 300. A braking actuator 106 for a wheel may be carriedwithin the wheel. In some embodiments, a brake actuation mechanism (notshown) may be provided for each wheel 326, 327, 328, and may include abrake rotor rigidly affixed to the rotating wheel, a brake caliperrigidly affixed to the respective wheel rotation assembly and/or otherwheel mounting point, and a mechanism for applying force on the caliperto provide braking friction on the brake rotor and thus on the wheel. Insome embodiments, the brake actuation mechanism may include a hydraulicmechanism in lieu of a braking actuator 106, as part of a brakingactuator 106, and/or in addition to a braking actuator 106. In someembodiments, the brake mechanism may be independently actuated by ahuman operator and/or the electronic controller, including processinglogic provided on vehicle 300, such that either the human or thecontroller may fully stop the vehicle.

Other suitable suspension assemblies may be provided for coupling thewheels of vehicle 300, for example first and second wheels 326, 327, tochassis 322. For example, a suspension assembly may be provided forcausing the wheels coupled thereto to pivot and/or tilt, for exampleabout an axis substantially parallel to and/or along the direction oftravel of vehicle 300, during turning of the wheels. In someembodiments, the wheels may tilt substantially in unison with thetilting of chassis 322 of vehicle 300, for example during turning.

One suitable suspension assembly 431 is illustrated in FIG. 4, wherelike reference numbers have been used to describe like components ofsuspension assemblies 331 and 431. In some embodiments, each of firstand second wheels 326, 327 is rotatably coupled, for example by asuitable wheel rotation assembly 346, to a suitable pivot assembly, forexample pivot assembly 336. For example, in the manner discussed above,each pivot assembly 346 permits the respective wheel 326, 327 to pivotand/or turn relative to suspension assembly 431 and thus to vehicle 300.

Suspension assembly 431 may include a central element 432 that may berigidly coupled and/or otherwise secured to chassis 322 so as to tilt inunison with chassis 322 during turning and/or certain other operationsof vehicle 300. In some embodiments, pivot assemblies 336 extendsubstantially parallel to each other, and to central element 432, duringturning and/or certain other operations of vehicle 300. Suspensionassembly 431 may include a pair of upper suspension arms for couplingthe top of each pivot assembly 336 to the top of central element 432,and a pair of lower suspension arms for coupling the bottom of eachpivot assembly to the bottom of central element 432. For example, anupper first suspension arm 433 may be provided and have an inner endpivotably coupled to the top of central element 432, for example atpivot element or pin 434, and an outer end pivotably coupled to the topof first pivot assembly 336, for example at pivot element or pin 436. Anupper second suspension arm 441 may be provided and have an inner endpivotably coupled to the top of central element 432, for example atpivot element 434, and an outer end pivotably coupled to the top ofsecond pivot assembly 336, for example at pivot element or pin 442. Alower first suspension arm 446 may be provided and have an inner endpivotably coupled to the bottom of central element 432, for example atpivot element or pin 447, and an outer end pivotably coupled to thebottom of first pivot assembly 336, for example at pivot element or pin448. A lower second suspension arm 451 may be provided and have an innerend pivotably coupled to the bottom of central element 432, for exampleat pivot element 447, and an outer end pivotably coupled to the bottomof second pivot assembly 336, for example at pivot element or pin 452.In some embodiments, each set of upper and lower suspension arms extendparallel to each other. For example, upper first suspension arm 433 mayextend parallel to lower first suspension arm 446, and upper secondsuspension arm 441 may extend parallel to lower second suspension arm451. In this regard, for example, central element 432 may have a lengthapproximately equal to the length of either pivot assembly 336.

The pivotable coupling of each suspension arm to central element 432 andits respective pivot assembly 336 causes each pivot assembly topassively tilt substantially in unison with central element 432, andthus with chassis 322. Such pivotable coupling of each suspension arm tocentral element 432 and its respective pivot assembly may additionallypermit relative upward and downward movement between central element 432and the respective pivot assembly, for example to accommodate bumps orobstacles encountered by the respective wheel during operation ofvehicle 300.

Any suitable steering mechanism or assembly 356 may be provided forcausing each of first and second wheels 326, 327 to pivot about therespective end of the suspension assembly 431 so as to permit steeringof the vehicle 300. In some embodiments, a steering mechanism orassembly 356 includes first and second steering rods 357, 358, which maybe coupled in any suitable manner to steering shaft 359 so that rotationof steering shaft 359 causes steering rods 357, 358 to move laterallyrelative to the steering shaft, causing wheels 326, 327 to pivotsubstantially in unison about the pivot axis of the respective pivotassembly 336. In some embodiments, each of the steering rods 357, 358has an outer end pivotably coupled in any suitable manner to therespective pivot assembly 336, for example to an arm 361 extendingperpendicularly from the pivot assembly, for causing such pivotingand/or steering of the respective wheel 326, 327.

Chassis 322 of the vehicle 300 may be pivotably coupled to suspensionassembly 431 by any suitable pivot assembly 461, for example a pivotassembly that includes pivot elements 434, 447 for permitting chassis322 to tilt relative to suspension assembly 431. Pivot assembly 461 maybe driven by one or more motors or actuators 102, which may optionallybe controlled by the computer network of the present disclosure, ormotorized or actuated, for tilting chassis 322 relative to the surfaceon which the wheeled vehicle is traveling and/or to any reference lineor plane 462 extending substantially parallel to such a surface. Each ofthe one or more motors or actuators may be referred to as a tiltingactuator 102. In some embodiments, one or more tilting actuators 102 maybe carried by chassis 322 for causing the chassis to tilt relative tosuspension assembly 431, and thus cause the chassis to tilt relative tothe surface on which the vehicle 300 is traveling, and/or to referenceline 462. For example, a tilting actuator may be provided in thevicinity of one or both of pivot elements 434, 447. For example, asshown in FIG. 4, a first tilting actuator 463 may be carried by centralelement 432, suspension 446, or both, for causing relative pivotalmovement between central element 432 and suspension arm 446 about pivotelement 447. Such relative pivotal movement between central element 432and suspension arm 446 may passively cause relative pivotal movementbetween central element 432 and suspension arm 433 about pivot element434. Similarly, a second tilting actuator 464 may be carried by centralelement 432, suspension 451, or both, for causing relative pivotalmovement between central element 432 and suspension arm 451 about pivotelement 447. Such relative pivotal movement between central element 432and suspension arm 451 may passively cause relative pivotal movementbetween central element 432 and suspension arm 441 about pivot element434.

In operation and use of vehicle 300, the one or more tilt actuators 102may cause chassis 322 to tilt relative to the surface on which thevehicle is traveling, or relative to a plane or line, such as referenceline 462 extending substantially parallel to the travel surface. Thedegree of such tilt may be controlled in any suitable manner, forexample, by the computer network of the present disclosure, includingvehicle controller 111 (see FIG. 5). For example, during the turning ofvehicle 300, while lateral accelerations and/or centrifugal forces areexerted on chassis 322, vehicle controller 111 and/or other aspects ofthe computer network of the present disclosure may direct the one ormore tilt actuators 102 to pivot and/or tilt chassis 322 so as tocompensate in whole or in part for such lateral accelerations and/orcentrifugal forces. The computer network, for example vehicle controller111, may receive input from one or more sensors, for example one or moreof sensors 121 (see FIG. 5), to measure such accelerations, centrifugalforces and/or other characteristics of chassis 322 so as to determinethe degree, amount, and/or angle to which chassis 322 should be pivotedand/or tilted by the one or more tilt actuators 102. For example, an IMUsensor, which may be included in the one or more sensors 121, and mayoptionally include a solid-state accelerometer, may be utilized formeasuring any suitable acceleration and/or force in this regard. Thedegree, amount, and/or angle of such tilt may be sensed and/or measuredby any suitable sensor, for example a sensor included in the one or moresensors 121, and directed back to controller 111 or other aspects of thecomputer network as feedback. Any suitable algorithm may be programmedinto the computer network, either as firmware, software or both, foranalyzing the input signals provided by one or more sensors and forinstructing and/or controlling the one or more tilt actuators 102.

Turning now to FIG. 5, a controller 111 of vehicle 300 may includeprocessing logic of any suitable configuration located on vehicle 300.In some embodiments, controller 111, which may be referred to as acomputer or computerized controller, may include a processor 112 and astorage or memory 113 of any suitable type. The processing logic ofcontroller 111 may be electronically coupled, for example electrically,optically, wirelessly, etc., to any or all of the electrically-operatedcomponents, mechanisms, or devices of vehicle 300 so as to permit theprocessing logic to control such components, mechanisms, or devices. Forexample, the controller may be electronically coupled to any or all ofthe actuators of the vehicle, for example any or all of actuators 396,101, 102 and 106. The processing logic or controller 111 may include areceiver and/or antenna 470 for receiving commands from a remote source,which may be sent by controller 111 to one or more of the actuatorsand/or other electronically-controlled mechanisms or devices of vehicle300.

In some embodiments, controller 111 may optionally be provided withinput signals from a global positioning system (GPS) device or receiver116 of any suitable type. In some embodiments, controller 111 mayutilize input signals from one or more sensors 117 of any suitable type,including for example one or more vision or other cameras, one or moreLIDAR devices or sensors, one or more sonar devices or sensors, one ormore radar devices or sensors, one or more near infrared (NIR) devicesor sensors, an inertial measurement unit (IMU) device or sensor, asensor for measuring lateral accelerations on the chassis and/orvehicle, a solid-state accelerometer, or any combination of theforegoing. Sensors 117 may be referred to as high-level sensors. Sensors117 may be part of controller 111, part of a robot computing system,part of a perception system (e.g., a computer vision system), and/or anycombination of the foregoing. In some embodiments, controller 111 mayoptionally include at least one transceiver and/or antenna 470 of anysuitable type, which may optionally include a Long-Term Evolution (LTE)and/or other cellular transmitting and receiving device, a wirelesslocal area networking (Wi-Fi) transmitting and receiving device, aBluetooth® protocol transmitting and receiving device, a radio frequency(RF) transmitting and receiving device, a low-power radio frequencytransmitting and receiving device, or any combination of the foregoing.Controller 111 may have fewer electronic components than described aboveor additional components not described above. Controller 111 may becarried anywhere on vehicle 300. Sensors 117 may be carried and/orprovided anywhere on vehicle 300, for example on one or more ends of thevehicle, one or more sides of the vehicle, or any combination theforegoing.

Vehicle 300 may optionally include one or more sensors 121 for detectingphysical characteristics of the vehicle, for example while the vehicleis at rest, during operation of the vehicle, or both. Sensors 121 may bereferred to as low-level sensors. Sensors 121 may optionally include asuitable odometry sensor provided on or with respect to each wheel ofvehicle 300, including for example on or with respect to any or all ofwheels 326, 327 and 328, for sensing rotary motion of the wheels. Forexample, such a rotary sensor could be provided on one or more of wheelrotation assemblies 346. Sensors 121 may optionally include a suitableangular or other position sensor provided on each joint or linkage ormovable member of vehicle 300, including for example pivot assembly 336,wheel rotation assembly 346, first steering rod 357, second steering rod358, steering shaft 359, coupling bracket 362, fork 376, pivot assembly377, pivot assembly 386, chassis 322, or any combination of theforegoing, for detecting or sensing movement or position of such member.Sensors 121 may optionally include at least one sensor coupled betweenvehicle chassis 322 and the suspension assembly for wheels 327, 328 fordetecting the relative angle between them. Sensors 121 may optionallyinclude at least one sensor coupled to the tilt rotational joint orpivot assembly for detecting the vehicle tilt angle. Sensors 121 mayoptionally include at least one sensor coupled to wheel rotationassembly 346 of any or all of wheels 326, 327, 328 for detecting theposition and velocity of the rotation of the respective wheel. Sensors121 may optionally include at least one sensor for each unactuated orpassive joint in the vehicle, for example in the suspension assembly331, for detecting the vehicle and/or chassis pose as a passive jointrotates or pivots.

Sensors 117 and 121 may optionally be electrically coupled to thecontroller of the present disclosure, for example controller 111, eitherdirectly or indirectly, so that the signals therefrom may be utilized bycontroller 111 and/or any aspect of the controller of the presentdisclosure in the operation of system of the present disclosure,including the operation of vehicle 300. For example, the input signalsfrom sensors 117 may be used by processing logic of the controller ofthe present disclosure for navigating vehicle 300. The input signalsfrom sensors 121 may be used for accomplishing such navigation, forexample monitoring and controlling the mechanical characteristics ofvehicle 300 during its use.

Vehicle 300, as so controlled by actuators such as any or all ofactuators 396, 101, 102 and 106 and any other electronically controlleddevice, may be referred to as a fly-by-wire vehicle. Such a fly-by-wirevehicle may be controlled electronically, for example by the computernetwork of the present disclosure, which may include one or morecomputers or other processing logics which may include onboardcontroller 111. The operation of such a fly-by-wire vehicle may beautonomous, for example without input from a human on the vehicle or ahuman remote of the vehicle. In such an autonomous operation of vehicle300, the vehicle is controlled entirely by the computer network of thepresent disclosure, which may include onboard controller 111. Theoperation of such a fly-by-wire vehicle may be semiautonomous, forexample controlled partially by the computer network of the presentdisclosure, which may include onboard controller 111, and partially byone or more humans, who may be on the vehicle, remote to the vehicle orboth.

Autonomous or semiautonomous operation of vehicle 300 may include thecontroller of the present disclosure directing one or more driveactuators 396 to move the vehicle in a direction or along a path oftravel, for example along an X-axis, an orthogonal Y-axis or both. Insome embodiments, the drive actuators 396 may selectively cause vehicle300 to move forward or backward. One or more steering actuators 101 ofthe vehicle 300 may be controlled by the controller to cause turning ofthe vehicle and thus the path of travel of the vehicle. One or morepivot assemblies of vehicle 300, for example one or more pivotassemblies 336, may be controlled by the controller, which may directone or more steering actuators 101 to cause pivoting of the vehicleabout an axis, for example a Y-axis, during turning of the vehicle.Pivoting of the vehicle may be caused by pivoting of one or more of thewheels, for example about a pivot assembly 336. One or more brakingmechanisms of vehicle 300 may be controlled by the computer network, forexample by means of one or more brake actuators 106, to cause slowing ofthe vehicle along its direction or path of travel. One or more pivot ortilt assemblies of vehicle 300, for example one or more tilt assemblies386, may be controlled by the computer network, for example by means ofone or more tilting actuators 102, to cause pivoting or tilting of thevehicle, for example chassis 322 of the vehicle, about an axis, forexample an X-axis.

In some embodiments, such a fly-by-wire vehicle 300 may be operatedmanually, either partially or completely, for example by a human ridingon the vehicle. In some embodiments, the onboard human may manuallycontrol one or all of the electronic actuators or otherelectronically-controlled devices of the vehicle, for example any or allof actuators 396, 101, 102 and 106, for example by providing manualinputs to the computer network of the present disclosure, providingmanual inputs to one or all of such electronic actuators or otherelectronically-controlled devices, manually controlling hydraulic orother non-electronic control mechanisms or devices of the vehicle, orany combination of the foregoing. For example, an onboard human maymanually tilt the vehicle, for example during turning of the vehicle, byshifting his or her weight, controlling his or her pose on the vehicle,or by any other known method for tilting a two-wheeled, three-wheeled orother vehicle during turning or otherwise. For example, an onboard humanmay manually steer the vehicle, for example during turning of thevehicle, by manually pivoting, rotating or moving handlebars, a steeringwheel or any other known mechanism for turning one or more wheels of avehicle.

Any suitable method or process may be utilized for operating vehicle300. One suitable method for operating vehicle 300, including bothautonomous and semiautonomous aspects of operating the vehicle and humanoperation of the vehicle, is discussed below. See also FIGS. 35-36 andassociated description.

In one optional step of the method, one or more operating mechanismsenable either autonomous or semiautonomous operation of vehicle 300, oralternatively enable partial or complete operation of the vehicle by ahuman carried by vehicle 300. The mechanism may operate in any suitablemanner. For example, the mechanism may direct autonomous orsemiautonomous operation of vehicle 300 unless directed by the onboardhuman to permit partial or complete human control of vehicle 300.

If autonomous or semiautonomous control of the vehicle is desired, inone optional step vehicle 300 is directed by a computer network totravel over a transportation network from a first location to a secondlocation. In another optional step, controller 111 relays drivinginstructions to vehicle 300 during the course of travel from the firstlocation to the second location. In another optional step, vehicle 300(e.g., onboard controller 111) receives the driving instructions andsends appropriate commands to the one or more drive actuators 396 andsteering actuators 101 to control the respective speed and direction oftravel of the vehicle. In one optional step, onboard controller 111receives input signals from GPS receiver 116, one or more of sensors117, or both, for use in charting the course of travel from the firstlocation to the second location. In another optional step, vehicle 300receives input signals from one or more sensors 121 that may measure thelateral accelerations and/or centrifugal forces exerted on the vehicleduring turns. In another optional step, vehicle 300, for example onboardcontroller 111, sends appropriate commands to the one or more tiltactuators 102 to pivot and/or tilt chassis 322 of the vehicle relativeto the travel surface and/or appropriate reference line or plane into aturn so as to compensate for such lateral accelerations and/orcentrifugal forces. In another optional step, the onboard controller 111relays instructions to vehicle 300 to slow the vehicle. In anotheroptional step, vehicle 300, for example onboard controller 111, receivesthe instructions from a computer network and sends commands to theappropriate one or more brake actuators 106, which cause such one ormore actuators to slow or stop the vehicle.

If partial or complete human control of the vehicle is desired, in anoptional step the onboard human relays drive instructions to vehicle 300during the course of travel from a first location to a second location.In another optional step, vehicle 300, for example onboard controller111, receives the driving instructions from the human and sendsappropriate commands to the one or more drive actuators 396 to controlthe speed of the vehicle. In another optional step, the one or moresteering actuators 101 are deactivated and/or overridden, for example byan operating mechanism under the direction of onboard controller 111, topermit the onboard human to manually steer the vehicle, for example byutilizing steering mechanism 356 to cause first and second wheels 326,327 to turn. In another optional step, the one or more tilt actuators102 are deactivated and/or overridden, for example by an operatingmechanism under the direction of onboard controller 111, to permit theonboard human to manually tilt chassis 322 of vehicle 300 into a turn tocompensate for lateral accelerations and/or centrifugal forces exertedon the human and/or vehicle during such turning. If vehicle 300 does notinclude electronic brakes but for example instead includes hydraulicbrakes, the human may actuate the nonelectronic brakes of the vehicle,which causes the vehicle to slow or stop. If vehicle 300 does includeelectronic brakes, in an optional step the human may relay brakeinstructions to the vehicle. In an optional step, vehicle 300, forexample onboard controller 111, receives the instructions from acomputer and sends commands to the appropriate one or more brakeactuators 106, which cause such one or more actuators to slow or stopthe vehicle.

As may be seen, the operating mechanism permits a partial or totalfly-by-wire vehicle, such as vehicle 300, to be operated solely by ahuman, or alternatively autonomously or semi-autonomously controlled bya controller, which may include an onboard electronic controller orcomputer, such as processing logic of controller 111. The vehicle may beentirely fly by wire, that is totally controlled by actuators instructedby electronic signals, or controlled both by such actuators and byactuators that are not electronically controlled, for examplehydraulically controlled brake or other actuators.

Turning now to FIGS. 6-26, various examples will now be discussed withrespect to optional tilt actuation mechanisms (i.e., examples of tiltactuator 102) suitable for use with tiltable wheeled vehicles of thepresent disclosure. Suitable mechanisms will also be discussed regardingsteering actuator 101 and others.

FIGS. 6-11 depict a first set of examples with respect to tilt actuator102, wherein the tilt actuator comprises a motor coupled to a set ofgears. FIGS. 6 and 7 are schematic views of a vehicle 600 having atiltable frame or chassis 602 and four-bar wheel linkage 604 couplingthe chassis to a pair of wheels 606, such that the wheels tilt in unisonwith the chassis. In this example, a motor 608 (e.g., a stepper motor,servo motor, or the like) is fixedly coupled to chassis 602 andcontrolled by a controller (e.g., controller 111). Motor 608 drives aspur gear 610, which is operatively connected with a larger gear 612having a half-circle shape (depicted as transparent in the drawings)that is fixed to a lower bar of the linkage. The lower bar is coupled towheels 606, which are resting on a support surface (not shown).Accordingly, as shown in FIG. 7, selective rotation of spur gear 610 bymotor 608 causes chassis 602 to tilt relative to the lower bar in acontrolled manner. The mechanics of the linkage also result in acorresponding tilt of wheels 606.

In some examples, gears 610 and/or 612 may be packaged or configureddifferently, such as in a gearbox, as a planetary gear assembly, etc. Inthe example depicted in FIGS. 8 and 9, a vehicle 600′ has a tiltableframe or chassis 602′ and four-bar wheel linkage 604′ coupling thechassis to a pair of wheels 606′, such that the wheels tilt in unisonwith the chassis. In this example, a motor 608′ (e.g., a stepper motor,servo motor, or the like) is coaxially mounted with a pivoting joint ofchassis 602′ and controlled by a controller (e.g., controller 111).Motor 608′ may be coupled directly to the joint or via a gearingassembly, e.g., a gearbox 610′ fixed to a lower bar of the linkage. Thelower bar is coupled to wheels 606, which are resting on a supportsurface (not shown). Accordingly, as shown in FIG. 9, selective rotationof the motor and gear assembly causes chassis 602′ to tilt relative tothe lower bar in a controlled manner. The mechanics of the linkage alsoresult in a corresponding tilt of wheels 606′.

In another example, FIGS. 10 and 11 depict a vehicle 600″ having atiltable frame or chassis 602″ and four-bar wheel linkage 604″ couplingthe chassis to a pair of wheels 606″, such that the wheels tilt inunison with the chassis. In this example, a motor 608″ (e.g., a steppermotor, servo motor, or the like) is fixedly coupled to a lower bar oflinkage 604″ and controlled by a controller (e.g., controller 111).Motor 608″ drives a spur gear 610″, which is operatively coupled with alarger gear 612″ affixed to chassis 602″ (e.g., coaxially with a lowerpivot joint between the chassis and linkage). The lower bar is coupledto wheels 606″, which are resting on a support surface (not shown).Accordingly, as shown in FIG. 11, selective rotation of spur gear 610″by motor 608″ causes chassis 602″ to tilt relative to the lower bar in acontrolled manner. The mechanics of the linkage also result in acorresponding tilt of wheels 606″.

FIGS. 12-15 depict a second set of examples with respect to tiltactuator 102, wherein the tilt actuator comprises a belt or chain drivemechanism. FIGS. 12 and 13 are schematic views of a vehicle 1200 havinga tiltable frame or chassis 1202 and four-bar wheel linkage 1204coupling the chassis to a pair of wheels 1206, such that the wheels tiltin unison with the chassis. In this example, a motor 1208 (e.g., astepper motor, servo motor, or the like) is fixedly coupled to chassis1202 and controlled by a controller (e.g., controller 111). Motor 1208drives a spur gear 1210, which is operatively connected by a belt orchain to a larger gear 1214 coaxially mounted to a pivoting jointbetween the upper bar of the linkage and the chassis. As shown in FIG.13, selective rotation of spur gear 1210 by motor 1208 causes chain 1212to rotate gear 1214, thereby applying rotation-inducing torque to thejoint and causing chassis 1202 to tilt in a controlled manner. Themechanics of the linkage also result in a corresponding tilt of wheels1206.

FIGS. 14 and 15 are schematic views of a vehicle 1200′ having a tiltableframe or chassis 1202′ and four-bar wheel linkage 1204′ coupling thechassis to a pair of wheels 1206′, such that the wheels tilt in unisonwith the chassis. In this example, a motor 1208′ (e.g., a stepper motor,servo motor, or the like) is fixedly coupled to an upper bar of thelinkage and controlled by a controller (e.g., controller 111). Motor1208′ drives a spur gear 1210′, which is operatively connected by a beltor chain to a larger gear 1214′ coaxially mounted to a pivoting jointbetween the lower bar of the linkage and the chassis. As shown in FIG.15, selective rotation of spur gear 1210′ by motor 1208′ causesbelt/chain 1212′ to rotate gear 1214′, thereby applyingrotation-inducing torque to the lower joint and causing chassis 1202′ totilt in a controlled manner. The mechanics of the linkage also result ina corresponding tilt of wheels 1206′.

FIGS. 16-23 depict a third set of examples with respect to tilt actuator102, wherein the tilt actuator comprises a linear actuator mechanismcoupled between two articulating elements of the vehicle. FIGS. 16 and17 are schematic views of a vehicle 1500 having a tiltable frame orchassis 1502 and four-bar wheel linkage 1504 coupling the chassis to apair of wheels 1506, such that the wheels tilt in unison with thechassis. In this example, a linear actuator 1508 (e.g., a piston, a rackand pinion, a worm screw, or the like, actuated electrically,hydraulically, or by any other suitable method) is coupled betweenchassis 1502 and a (e.g., lower) bar of the linkage, and controlled by acontroller (e.g., controller 111). As depicted, linear actuator 1508 iscoupled at a first end by a pivoting joint 1510 to linkage 1504 and at asecond end by a pivoting joint 1512 to chassis 1502. As shown in FIG.17, selective linear actuation of linear actuator 1508 causes chassis1502 to be urged toward or away from the lower bar of the linkage, totilt in a controlled manner. The mechanics of the linkage also result ina corresponding tilt of wheels 1506.

FIGS. 18-23 depict further examples where tilt actuator 102 comprises alinear actuator. In these examples, one end of the linear actuator isfixed while the other end is a pivoting or a pivoting and sliding joint.More specifically, FIGS. 18 and 19 depict a linear actuator 1508′ fixedat a first end 1510′ to linkage 1504′ and in a pivotable fashion at asecond end 1512′ to a side bar of the linkage. FIGS. 20-21 depict asimilar linear actuator 1508″ fixedly coupled at a first end 1510″ to alower bar of linkage 1504″ and slidingly coupled at a pivotable secondend 1512″ to a side bar of the linkage.

FIGS. 22-23 depict another example where multiple (here, two) linearactuators may be utilized in tandem. Specifically, a vehicle 1500′″includes a tiltable chassis 1502′″ that may be urged side to side by apair of opposing linear actuators 1508′″ and 1514′″, each of which iscoupled between a lower bar of the linkage and the central chassis.

FIGS. 24A and 24B depict yet another example of a wheeled vehicle 2400,in this case having a chassis comprising a tiltable frame 2402 pivotablewith respect to a stationary (i.e., non-rotating) frame 2414 at a pivotjoint 2412. Vehicle 2400 further comprises a four-bar linkage 2404coupling the chassis to a pair of wheels 2406 configured to tilt inunison with frame 2402. Here, each lateral half of the four-bar linkageis rotatably linked to the chassis at an upper joint 2416 and at a lowerjoint 2418, and damped by an A-frame shock absorption system comprisinga stationary central riser and a pair of springs or shock absorbers 2408(one on either side of the riser) connected between the riser and thelower bars of the linkage. The riser is a vertical extension ofstationary frame 2414. In this example, an actuator 2410 (here shown asa motor and spur gear assembly, but any suitable actuator may beutilized) is coupled between tiltable frame 2402 and stationary frame2414, and configured to cause relative motion between the two (e.g., byapplying a tilt-inducing force to frame 2402). A linear actuator,belt/chain drive, or the like may also be used. In this example,selective rotation of the spur gear by the motor transfers rotationalforce to the larger gear, and causes tiltable frame 2402 to tiltrelative to stationary frame 2414 in a controlled manner. As depicted inFIGS. 24A and 24B, the mechanics of the linkage result in acorresponding tilt of wheels 2406.

FIG. 25 depicts an example of steering actuator 101. In this example, awheeled vehicle 2500 includes a servo motor 2502 controlled by acontroller to selectively rotate a first gear 2504 coupled to a secondgear 2506 that is mounted coaxially with respect to a steering member2508. Steering member may accordingly be rotated automatically by motor2502 via gears 2504 and 2506, or manually using a handlebar 2510.Steering may also be controlled using any other suitable version ofactuator described herein, e.g., coupled to the steering linkage or tierod.

The throttle and/or braking systems may also be controlled autonomouslyor semi-autonomously, e.g., using software to control appropriateactuators.

FIG. 26 depicts another example of a tiltable vehicle 2600,substantially as described above, but with a steering wheel 2602 and acanopy or windshield enclosure 2604. Steering wheel 2602 may bemechanically coupled to the wheel linkage of the vehicle, and/or may bein (e.g., wireless) communication with a controller of the vehicle tocommand a steering actuator.

Various aspects of the actuators described herein may be replaced withor supplemented by series elastic actuators (SEAs), which include anelastic element in series between the force-producing portion of thesystem and the thing being actuated. This elastic element may allow theforce production to continue without incident even if the thing beingactuated is impeded or opposed by an outside object or force. An SEA mayimprove ride feel, increase safety, and/or prevent damage to structuresor motors in high stress situations such as when hitting potholes.

B. Illustrative Control Methods

This section describes steps of illustrative methods for controlling atiltable vehicle; see FIGS. 27-37. Aspects of vehicles described abovemay be utilized in the method steps described below. Where appropriate,reference may be made to components and systems that may be used incarrying out each step. These references are for illustration, and arenot intended to limit the possible ways of carrying out any particularstep of the method.

Generally speaking, a desired tilt angle for the vehicle in question isderived by determining what side-to-side lean or tilt angle results in anet force vector aligned with the central vertical plane of the chassis,also referred to as the median plane, i.e., a plane through the verticalcenterline of the vehicle dividing or bisecting the chassis into leftand right portions (XZ when the chassis is vertical). The net forcevector is defined as the combined force vector resulting from downwardgravity and lateral centrifugal force. A sensor (e.g., an accelerometer)on the vehicle detects lateral deflection of the force vector on thechassis (e.g., due to centrifugal forces from initiating a steered turn,or lateral forces from uneven terrain during a turn or during normaloperation). In response, a tilting actuator and in some cases a steeringactuator are adjusted to return the net force vector to substantialalignment with the median plane of the chassis. Lean angle changes withspeed and tightness of turn radius. Given the desired or optimum tiltangle for a given turn radius and/or speed, (i.e., the angle that keepsthe net force vector in alignment with the chassis) the tilt linkage maybe altered to maintain that tilt angle, and also to keep the tilt angleregardless of uneven/changing ground surface.

Additionally or alternatively, a substantially similar system may beutilized to control a fore/aft tilt angle, i.e., maintaining a secondnet force vector in line with a second vertical plane cutting laterallythrough the chassis and dividing the chassis into front and rearportions, also referred to as the frontal plane (YZ when the chassis isvertical). For example, this second system may be utilized to maintain adesired chassis angle when traveling uphill or downhill. The discussionbelow describes a side-to-side tilt control system, but the sameprinciples may be applied to a fore/aft tilt system.

Lean (AKA tilt) to steer ratios are calculated to maintain the summaryforce vector (with respect to centrifugal force and the force due togravity) in alignment with the median plane of the tilting vehicle.Generally speaking, the faster the vehicle goes for any given turnradius, the more the vehicle chassis needs to lean in order to keep thissummary force vector in alignment with the median plane of the tiltablechassis. Higher speed or decreased turning radius results in an increaseto the desired lean angle. Given the dynamic nature of drivingconditions, one or more sensors are employed to ensure desiredperformance.

Rider experience (or the forces on the vehicle load during transport) isgenerally improved by aligning the net force vector with the chassis.Even with higher net forces, if the forces are aligned with the chassistilt then the effect is basically an increase in G forces, rather than asubjective experience of tipping or sliding. However, values may betuned to produce different modes, e.g., a sport mode with a moreaggressive, amplified responsiveness (e.g., turning tighter for a givenlean angle) or over-steering/understeering to produce various handlingcharacteristics.

The controller(s) of the vehicle tilt/steer system may include anysuitable processing logic configured to carry out algorithms such asthose described herein. For example, a PID (proportional integralderivative) controller may be utilized, having a control loop feedbackmechanism to control tilt/steer variables based on force vectormeasurement. In general, the process steps described below areillustrated by accompanying FIGS. 27-34 and outlined in FIGS. 35-36. Asdescribed above, a vehicle 2700 being controlled has at least a pair ofwheels 2702 or other travel surface interfaces configured to tilt withthe central chassis 2704, e.g., using a four-bar linkage 2706, as wellas one or more tilt sensors 2708 (e.g., accelerometers, gyroscopes,etc.), steering actuators 2710, and tilt actuators 2712 controlled by acontroller 2714 (e.g., an onboard controller). The general example usedhere is a three-wheeled vehicle with a tilting pair of wheels in thefront, a geared tilt mechanism, and an in-line servo motor forcontrolled steering. However, any suitable arrangement may be utilized,as described throughout this disclosure.

Three basic modes may be utilized when controlling vehicle 2700, whichis an example of the vehicles described elsewhere in this disclosure.First, both the chassis tilt and the steering may be powered andactively controlled. Second, only tilt may be powered. A third mode mayinclude powered tilting with variable levels of steering control (e.g.,based on vehicle speed).

In general, a user (e.g., using a steering wheel, joystick, or otherinterface) or an automated or semiautomated vehicle controllerdetermines and/or indicates a desired vehicle path. Proper lean to steerratios are then calculated based on the given speed. Chassis tilt and/orsteering are then actuated in parallel accordingly, to maintain the netforce vector in line with the median plane of the chassis. Terrainadjustments are made based on feedback from the measured chassis tilt.Two suitable control schemes are described below, with respect to FIGS.35 and 36.

B1. Lean Follows Steer (LFS)

In a first control scheme, vehicle tilt follows vehicle steering. Inother words, the wheels are steered first when entering a turn, and thevehicle chassis is caused to tilt automatically in response to thecentrifugal force, such that the forces balance and the net force vectordue to gravity and centrifugal force remains in line with the medianplane of the tilting chassis.

FIG. 35 is a flowchart illustrating steps performed in an illustrativemethod 3500 implementing an LFS control scheme, and may not recite thecomplete process or all steps of the method. Although various steps ofmethod 3500 are described below and depicted in FIG. 35, the steps neednot necessarily all be performed, and in some cases may be performedsimultaneously or in a different order than the order shown.

Step 3502 of method 3500 includes operating the vehicle (e.g., vehicle2700) along a straight path on a level surface. In this situation, thenet force vector is substantially equal to the force of gravity, and isaligned with the vertical chassis (see FIG. 27).

Step 3504 of method 3500 includes causing the wheels of the vehicle(e.g., wheels 2702) to turn, e.g., using steering actuator 2710, therebyimparting a centrifugal force and causing a change in the net forcevector on the vehicle (see FIG. 28). This step may be carried out by auser riding on the vehicle, e.g., using a steering mechanism such ashandlebars or a steering wheel, by a remote user in a fly-by-wirescenario using a remote control device, or by an automated onboardcontroller. Accordingly, the net force vector will no longer be alignedwith the median plane of the chassis.

Step 3506 of method 3500 includes sensing the misalignment between themedian plane of the vehicle and the net force vector due to thecentrifugal force and gravity. This step may be carried out by the tiltsensor (e.g., tilt sensor 2708).

Step 3508 of method 3500 includes causing the chassis (e.g., chassis2704) to tilt to compensate for the increased centrifugal force, i.e.,aligning the chassis such that the net force vector is in line with themedian plane. As described above, the four bar linkage of the vehiclewill cause the wheels to tilt with the chassis (e.g., to the samedegree). See FIG. 29.

Step 3510 of method 3500 includes causing the wheels of the vehicle toreturn to a neutral position to come out of the turn began in step 3504.As in that step, the wheels may be steered by a user and/or acontroller, e.g., using a steering actuator. This action causes thecentrifugal force to be reduced or eliminated, thereby causing anothermisalignment of the net force vector with respect to the still-leaningchassis. See FIG. 30.

Step 3512 of method 3500 includes causing the chassis to tilt in anupright direction to compensate for the mismatch between the forcevector and the median plane, e.g., using a controller to command thevehicle's tilt actuator. See FIG. 27.

B2. Steer Follows Lean (SFL)

In a second control scheme, vehicle steering follows vehicle tilt. Inother words, the vehicle is tilted when entering a turn, and in responsethe wheels naturally steer and/or are caused to steer, such that theforces balance and the net force vector due to gravity and centrifugalforce remains in line with the median plane of the tilting chassis. Inother words, the chassis tilts first, or at least simultaneously withthe wheels turning, and the wheels turn to a determined value that takesinto account vehicle speed and tilt angle. At higher speeds, steeringmay be in a “free-to-caster” (FTC) mode, meaning no torque is appliedand the wheels are left to move to a steering angle naturally. At lowerspeeds, steering may be completely controlled by a steering actuator(e.g., a servo motor). A transition zone or range between the lowerspeeds and the higher speeds, may also be defined, in which steeringcontrol is gradually transitioned from full torque to no torque, eitherlinearly or nonlinearly. For example, below approximately 10 miles perhour (mph), wheels of the vehicle may be completely controlled byapplying torque from a steering actuator. In this example, aboveapproximately 20 mph the wheels may be completely FTC. Betweenapproximately 10 mph and approximately 20 mph, control is transitionedfrom full-torque to zero-torque, e.g., using a clutch mechanism or thelike. At extremely low speeds (e.g., less than one mph), vehicle tiltingmay be locked. These speeds are for illustration only, and any suitablespeeds may be selected, depending on desired characteristics, vehiclecapabilities, and operating conditions.

FIG. 36 is a flowchart illustrating steps performed in an illustrativemethod 3600 implementing an SFL control scheme, and may not recite thecomplete process or all steps of the method. Although various steps ofmethod 3600 are described below and depicted in FIG. 36, the steps neednot necessarily all be performed, and in some cases may be performedsimultaneously or in a different order than the order shown.

As explained above, an SFL control scheme may include three stages,depending on vehicle speed and/or other factors (e.g., vehicle loading).In this example, step 3602 of method 3600 includes operating the vehicle(e.g., vehicle 2700) along a straight path on a level surface at a givenspeed. In this situation, the net force vector is substantially equal tothe force of gravity, and is aligned with the vertical chassis. See FIG.27.

Step 3604 of method 3600 includes responding to a signal to turn thevehicle (e.g., from a user or an automated guidance system) by causingthe chassis to tilt (e.g., using a tilt actuator) in a directionopposing the expected centrifugal force that will be caused by the turnand in an amount calculated to at least partially cause the turn tooccur. A mismatch will occur between the net force vector (due tocentrifugal force and gravity) and the median plane of the chassis. SeeFIG. 30.

If the speed of the vehicle is below a selected first threshold, thenstep 3606 of method 3600 includes causing the wheels to be steered(e.g., by issuing commands from a controller to a steering actuator)such that the net force vector aligns with the median plane, and thedesired turning path is substantially followed. Below the selected firstspeed threshold, the vehicle may be referred to as operating in a dualinput or dual control mode (i.e., tilt and steering are both controlledactively). See FIG. 29.

If the speed of the vehicle is above a selected second threshold, thenstep 3608 of method 3600 includes allowing the wheels to freely caster,i.e., applying zero additional torque to the wheels, thereby permittingthe wheels to find their natural positions as a result of the vehicle'stilt. Above the selected second speed threshold, the vehicle may bereferred to as operating in a free-to-caster or FTC mode (i.e., onlytilt is controlled actively). See FIG. 29.

If the speed of the vehicle is between the first and second thresholds,then step 3610 of method 3600 includes applying a selected amount oftorque to the steering system to maintain the turn and at leastpartially prevent wheel scrub with respect to the support surface. Inthis transition zone or transition range from full torque to zerotorque, the level of torque applied to the steering may be proportionalto vehicle speed (e.g., linearly related to speed or nonlinearly relatedto speed), depending on desired characteristics. See FIG. 29.

Step 3612 of method 3600 includes causing the tilt of the vehicle toreturn to a neutral position to come out of the turn began in step 3604.Depending on speed, as described above, the wheels may be steered moreor less actively to assist and maintain alignment of the net forcevector. See FIG. 30.

At very low speeds, e.g., below a third threshold (lower than the firstand second thresholds), chassis tilt may be held constant or locked inplace, such that only wheel steering may be utilized to achieve aselected vehicle path. See FIG. 28.

In some examples, aspects of methods 3500 and 3600 may be combined,e.g., such that the vehicle follows an LFS scheme when below the firstspeed threshold and a FTC scheme above the second threshold.

B3. Correcting for Terrain

Regardless of the control scheme, it may be instructive to describe howvehicles and control systems as described herein may be configured tohandle (automatically) terrain changes and minor obstacles, i.e.,non-planar travel surfaces. See FIGS. 31-34.

In general, a vehicle 3100 encountering an obstacle 3102 under one wheelor the other will be caused to tilt out of its commanded tilt value orrange, causing instability of the vehicle. Vehicle stability ismaintained and controlled by leaning a chassis 3104 of the vehiclerelative to a wheel linkage 3106, thereby permitting the wheel linkageto tilt as a result of the obstacle, while maintaining the angle of thechassis with respect to a horizontal plane (e.g., a plane orthogonal tothe force of gravity, or the idealized planar travel surface). This isaccomplished by maintaining an alignment between the net force vectorand the median plane of the chassis, as measured by the tilt sensor(s)of the vehicle.

For example, vehicle 3100 may be traveling either in a straight line(see FIG. 31) or in a turn (see FIG. 33), when obstacle 3102 isencountered. In either case, the obstacle initially causes chassis 3104to tilt out of alignment with the net force vector. The controller ofthe vehicle compensates for this misalignment by adjusting the tiltangle of the chassis until the net force vector again aligns with themedian plane. See FIGS. 32 and 34. As depicted, an initial angle A, B ofthe chassis with respect to horizontal is maintained by the controlsystem, while a linkage displacement angle T changes based on theterrain. Once the obstacle is overcome, the chassis will tilt again, andthe control system will adjust the tilt to compensate, returning to theoriginal configuration.

Terrain compensation may result in difficulty maintaining a desiredpath. Accordingly, regardless of mode, the control system may beconfigured to selectively apply torque to the steering system to handlethe dynamic conditions.

C. Illustrative Combinations and Additional Examples

This section describes additional aspects and features of tiltablevehicles and their control systems, presented without limitation as aseries of paragraphs, some or all of which may be alphanumericallydesignated for clarity and efficiency. Each of these paragraphs may becombined with one or more other paragraphs, and/or with disclosure fromelsewhere in this application, in any suitable manner. Some of theparagraphs below expressly refer to and further limit other paragraphs,providing without limitation examples of some of the suitablecombinations.

A0. A vehicle comprising:

a pair of wheels coupled to a tiltable central frame by a four-barlinkage configured such that the pair of wheels and the central frameare configured to tilt in unison with respect to a median plane of thecentral frame;

a sensor configured to detect directional information regarding a netforce vector applied to the central frame, wherein the net force vectoris determined by gravity in combination with any applicable centrifugalforce applied to the central frame;

a first actuator operatively coupled to the central frame and configuredto selectively tilt the central frame;

a second actuator operatively coupled to the pair of wheels andconfigured to selectively steer the pair of wheels; and

a controller including processing logic configured to selectivelycontrol the first actuator and the second actuator in response to thedirectional information from the sensor to automatically maintain thenet force vector in alignment with the median plane of the centralframe.

A1. The vehicle of A0, wherein the sensor comprises an accelerometer.

A2. The vehicle of A0 or A1, wherein the first actuator comprises aservo motor.

A3. The vehicle of any one of paragraphs A0 through A2, wherein thecontroller is configured to control the first actuator independently ofthe second actuator.

A4. The vehicle of any one of paragraphs A0 through A3, wherein theprocessing logic of the controller is further configured to respond to arequested travel path of the vehicle by controlling the second actuatorto steer the wheels and then to control the first actuator to tilt thecentral frame in response to a resulting misalignment between the netforce vector and the median plane of the central frame.

A5. The vehicle of any one of paragraphs A0 through A4, wherein theprocessing logic of the controller is further configured to respond to arequested travel path of the vehicle by controlling the first actuatorto tilt the central frame and then to control the second actuator tosteer the wheels in response to a resulting misalignment between the netforce vector and the median plane of the central frame.

A6. The vehicle of any one of paragraphs A0 through A5, wherein theprocessing logic of the controller is further configured to permit thepair of wheels to freely caster when a speed of the vehicle is above aselected threshold.

A7. The vehicle of A6, wherein the processing logic of the controller isfurther configured to control the second actuator to apply a selectedamount of steering torque to the pair of wheels when the speed of thevehicle is less than the selected threshold.

A8. The vehicle of A7, wherein the selected threshold is defined as afirst threshold, and the selected amount of steering torque is linearlyrelated to the speed of the vehicle when the speed is below the firstthreshold and above a second threshold.

A9. The vehicle of any one of paragraphs A0 through A8, furthercomprising a handlebar operatively coupled to the pair of wheels.

A10. The vehicle of any one of paragraphs A0 through A9, wherein thepair of wheels is coupled to the central frame at a first end, thevehicle further comprising a third wheel coupled to an opposite, secondend of the central frame.

A11. The vehicle of A10, wherein the third wheel is coupled to thesecond end at a pivotable joint.

A12. The vehicle of A11, wherein pivoting of the third wheel about thepivotable joint is damped by a spring disposed between the third wheeland the central frame.

B0. A method for automatically operating a tiltable vehicle, the methodcomprising:

sensing a net force vector on a central chassis of a wheeled vehicle,the central chassis coupled to a pair of laterally disposed wheels by afour-bar linkage assembly, wherein the central chassis is tiltable fromside to side and the four-bar linkage assembly is configured to tilt thewheels in unison with the central chassis, and wherein the centralchassis defines a median plane;

in response to receiving information relating to a desired travel path,comparing a speed of the vehicle to a first threshold and a secondthreshold greater than the first threshold; and

in response to the speed of the vehicle being less than the firstthreshold, turning the vehicle by simultaneously and automaticallysteering the wheels and causing a tilting of the central chassis, suchthat a misalignment between the net force vector and the median plane isminimized.

B1. The method of B0, further comprising:

in response to the speed of the vehicle being greater than the secondthreshold, automatically causing the central chassis to tilt to turn thevehicle, and, allowing the pair of wheels to freely caster.

B2. The method of B0 or B1, further comprising:

in response to the speed of the vehicle being between the firstthreshold and the second threshold, automatically actively steering thewheels by applying a selected amount of torque corresponding to thespeed of the vehicle.

B3. The method of B2, wherein the selected amount of torque is linearlyproportional to the speed of the vehicle.

B4. The method of B2, wherein the selected amount of torque correspondsto the speed of the vehicle in a nonlinear relationship.

B5. The method of any one of paragraphs B0 through B4, furthercomprising: in response to one of the wheels encountering an obstacleand causing a misalignment between the net force vector and the medianplane, automatically compensating by causing the central chassis to tiltinto alignment with the net force vector.

B6. The method of B5, further comprising causing the central chassis toreturn to an original orientation after clearing the obstacle

B7. The method of any one of paragraphs B0 through B6, furthercomprising propelling the vehicle using a powered third wheel coupled tothe central chassis.

B8. The method of any one of paragraphs B0 through B7, wherein the netforce vector is a result of gravity and a centrifugal force.

Advantages, Features, and Benefits

The different embodiments and examples of the vehicles and controlsdescribed herein provide several advantages over known solutions. Forexample, illustrative embodiments and examples described herein allowautomated or semiautomated control of a wheeled vehicle while maximizingrider comfort.

Additionally, and among other benefits, illustrative embodiments andexamples described herein automatically stabilize a robotic or othervehicle by tilting the vehicle from side to side to compensate forcentrifugal forces during transit.

No known system or device can perform these functions. However, not allembodiments and examples described herein provide the same advantages orthe same degree of advantage.

CONCLUSION

The disclosure set forth above may encompass multiple distinct exampleswith independent utility. Although each of these has been disclosed inits preferred form(s), the specific embodiments thereof as disclosed andillustrated herein are not to be considered in a limiting sense, becausenumerous variations are possible. To the extent that section headingsare used within this disclosure, such headings are for organizationalpurposes only. The subject matter of the disclosure includes all noveland nonobvious combinations and subcombinations of the various elements,features, functions, and/or properties disclosed herein. The followingclaims particularly point out certain combinations and subcombinationsregarded as novel and nonobvious. Other combinations and subcombinationsof features, functions, elements, and/or properties may be claimed inapplications claiming priority from this or a related application. Suchclaims, whether broader, narrower, equal, or different in scope to theoriginal claims, also are regarded as included within the subject matterof the present disclosure.

What is claimed is:
 1. A vehicle comprising: first and second wheelscoupled to a central frame by a four-bar linkage which allows the wheelsand the central frame to tilt with respect to a median plane of thecentral frame; a sensor configured to detect directional informationregarding a net force vector applied to the central frame; a firstactuator operatively coupled to the central frame and configured toselectively tilt the central frame; a second actuator operativelycoupled to the wheels and configured to selectively steer the wheels;and a controller including processing logic configured to selectivelycontrol the first actuator and the second actuator in response to thedirectional information from the sensor to automatically maintain thenet force vector in alignment with the median plane of the centralframe; wherein the processing logic of the controller is furtherconfigured to control the second actuator to automatically (a) apply aselected amount of steering torque to the wheels when a speed of thevehicle is less than a first threshold, and (b) permit the wheels tocaster freely when the speed of the vehicle is above the firstthreshold; and wherein the four-bar linkage includes a top suspensionbar, a bottom suspension bar, a left suspension bar and a rightsuspension bar, and wherein the top suspension bar includes a pair ofupper suspension arms each having an inner end coupled together at afirst pivot element.
 2. The vehicle of claim 1, wherein the four-barlinkage includes a central element rigidly coupled to the frame, andwherein the first pivot element is attached to the central element. 3.The vehicle of claim 1, wherein the four-bar linkage includes a centralelement rigidly coupled to the frame, and wherein the central elementincludes the first pivot element.
 4. The vehicle of claim 1, wherein thebottom suspension bar includes a pair of lower suspension arms eachhaving an inner end rotatably coupled together at a second pivotelement.
 5. The vehicle of claim 4, wherein the four-bar linkageincludes a central element rigidly coupled to the frame, and wherein thefirst pivot element and the second pivot element are rigidly coupled tothe central element.
 6. The vehicle of claim 5, wherein a first one ofthe pair of upper suspension arms extends parallel to a first one of thepair of lower suspension arms, and a second one of the pair of uppersuspension arms extends parallel to a second one of the pair of lowersuspension arms.
 7. A vehicle comprising: first and second wheelscoupled to a chassis by a four-bar linkage which enables the wheels andthe chassis each to tilt with respect to a median plane defined by thechassis; a sensor configured to detect lateral deflection of a net forcevector on the chassis; a tilting actuator operatively coupled to thechassis and configured to selectively tilt the chassis; and a motorizedsteering actuator operatively coupled to the wheels and configured toselectively steer the wheels; wherein at least one of the tiltingactuator and the steering actuator are configured to return the netforce vector to substantial alignment with the median plane of thechassis, in response to the sensor detecting lateral deflection of thenet force vector; wherein the four-bar linkage includes a top suspensionbar, a bottom suspension bar, a left suspension bar and a rightsuspension bar, and wherein the top suspension bar includes a pair ofupper suspension arms each having an inner end coupled together at afirst pivot element; and a controller, wherein processing logic of thecontroller is configured to control the steering actuator toautomatically (a) apply a selected amount of steering torque to thewheels when a speed of the vehicle is less than a first threshold, and(b) permit the wheels to caster freely when the speed of the vehicle isabove the first threshold.
 8. The vehicle of claim 7, wherein thelinkage includes a central element rigidly coupled to the chassis, andwherein the first pivot element is attached to the central element. 9.The vehicle of claim 7, wherein the linkage includes a central elementrigidly coupled to the chassis, and wherein the central element includesthe first pivot element.
 10. The vehicle of claim 7, wherein the bottomsuspension bar includes a pair of lower suspension arms each having aninner end coupled together at a second pivot element.
 11. The vehicle ofclaim 10, wherein the four-bar linkage includes a central elementrigidly coupled to the chassis, and wherein the first pivot element andthe second pivot element are rigidly coupled to the central element. 12.The vehicle of claim 11, wherein a first one of the pair of uppersuspension arms extends parallel to a first one of the pair of lowersuspension arms, and a second one of the pair of upper suspension armsextends parallel to a second one of the pair of lower suspension arms.